Mexican tycoon Carlos Slim, the world's third-richest man, called on US President George W. Bush to push more US investment in Latin America, where he is at odds with leftist leaders.

Hours ahead of a visit by Bush to Mexico, Slim said more investment in the region would bring down US corporate costs and stem the flow of immigrants crossing into the United States, often to flee from poverty.

"The United States should buy from and invest more in Latin America, pass a good part of its industry to our countries," the cigar-smoking Slim said in a four-hour news conference.

Slim, whose wealth from his telecommunications, retail and industrial firms is estimated at $49 billion by Forbes magazine, said US companies should build large, top-quality hospitals on the Mexican side of the 2,000-mile (3,200-km) border.

"This would reduce health costs in the United States," Slim said.

Cheaper Mexican salaries -- from construction workers to nurses -- would lower hospital costs and fees, he added.

Slim, 67, said the fence being built on the US-Mexico border to try to stop immigrants from entering the United States illegally was absurd.

US immigration policies are unpopular across much of Latin America, helping leftist leaders like Venezuelan President Hugo Chavez gain support in the region.

"What is needed is legal immigration, immigration accords, but not one just for highly qualified people," Slim said.

Bush said in Guatemala he wants a breakthrough on US immigration reform by August.

Mexico was the last stop on Bush's five-nation Latin American tour, a trip in which he has been dogged by thunderous denunciations from his leftist nemesis in the region, Chavez.

Bush failed to get an immigration overhaul through the then Republican-led Congress last year due to conservative concerns about a porous US-Mexico border.

Slim said Calderon had set out on the right footing with a major clampdown on drug trafficking and other violent crime in Mexico. Calderon has sent thousands of troops to states where drug gangs operate.

"I see it as very positive the vision that he has and the steps he is taking, especially on the crime front," Slim said.

Slim said Mexico, one of the biggest suppliers of crude oil to the United States, should invest more in energy exploration and production to convert itself into a more reliable provider of oil to its neighbor. (Reuters)